   "Retrieves items from a table (unindexed) with options:
     :attr-conds     - {<attr> [<comparison-operator> <values>] ...}.
     :limit          - Max num >=1 of items to eval (≠ num of matching items).
+                      Useful to prevent harmful sudden bursts of read activity.
     :last-prim-kvs  - Primary key-val from which to eval, useful for paging.
     :max-reqs       - Max number of requests to automatically stitch together.
     :return         - e/o #{:all-attributes :all-projected-attributes :count

                             :not-null :null :contains :not-contains :in}.

  For automatic parallelization & segment control see `scan-parallel`.
  For indexed item retrievel see `query`."
  [creds table
   & [{:keys [attr-conds last-prim-kvs max-reqs return limit total-segments
              segment return-cc?] :as opts


;;;; Misc. helpers

(defn items-by-attrs
  "Groups one or more items by one or more attributes, returning a map of form
  {<attr-val> <item> ...} or {{<attr> <val> ...} <item>}.
